HW Tank Installation Advice

It's been a while since I installed a HW tank, and this one is a little worrisome. It's below an old home in some sort of cellar. It's been leaking for about a month and has no shutoff valves of any kind. So it's like working in a very wet and muddy cave, and there's no light except what comes in from the one door.

All the fittings are corroded away to nothing, so I have to do a lot of extra plumbing. For the cold side, I'm thinking of cutting off the bad tee in the main line, which I believe is 3/4" PVC. I can use a compression tee or a cemented-in tee, and then use a CPVC adapter. I'll then install an in-line CPVC ball valve and some more CPVC and finally connect up to the 24" flex copper, which I'll connect to the new water tank.

For the hot side, I'm thinking of cutting off the bad el and cementing in a new el with a CPVC adapter and use a straight piece of CPVC to the flex copper.

Questions: Which is better, the compression tee or the cement-in tee? How long do I have to wait for the CPVC joints to set up before pressurizing the system? Is it necessary to have a ball valve on the hot side as well? The CPVC ball valves are only rated to 180 degrees.

The gas union is on the wrong side of the shutoff. It should be on the heater side of the shutoff and it looks like it is on the street / meter side. All you have to do is switch the places that they are located.

PVC is never alowed inside homes for pressurized water systems (to the best of my knowlage.)

go back as far as your budgit will alow. and replace as much of the pvc as you can. CPVC is the best thing out there for a home owner to use. I won't use it. It is legal in most states and is easy to use. Few plumbers will use it because it is brittle. Hit it with a hammer and you've got a mess.

Read the glue can it'll tell you how long to wait.

You don't need a ball valve on the hot side, but it doesn't hurt.

And I think sharkbite fittings only come in Copper Pipe sizes????? It shouldn't work on PVC??? Please correct me if I'm wrong.

"A lot of extra plumbing" is a gross understatement if you're going to get this mess straightened out. I'd say it's pretty obvious that this is an install done by someone totally unaware of codes. That pipe is not CPVC, it's PVC and that isn't allowed inside the house. PVC and CPVC are different materials and sizes, so you can just tie one to the other. I question that you can even legally have a gas heater in that location, but certainly if it is to be installed there, it needs a solid slab to set on. At the very least, the entire mess of pipes should be stripped out from the water source forward and properly plumbed. Personally, I'd use copper pipe and a ball valve for the water lines. That will still probably be second rate since the main supply is almost certainly ancient galvanized pipe and really due for replacment, but at least this job should be done as right as possible. You definitely need to see that the gas is correctly connected. I think the very first thing you should do is to check codes to see what, if anything, can be done with this.

Thanks for all the advice. I keep trying to tell you all that this area is like a third-world country. There's no codes or at least no code enforcement. I know the difference between PVC and CPVC, which is why I'm using only CPVC for my work.

The homeowner has no money to change over all of her plumbing. It took her a month to get the money to buy the tank, even though water has been pouring out of the bottom the whole time. I'll put on my rubber boots and do the best I can to get her some hot water.

Third world or not, the laws of physics still apply, so if that is the T&P safety valve in the first picture, replace it before the heater blows up and she doesn't have to worry about the rest of the plumbing.

Third world or not, the laws of physics still apply, so if that is the T&P safety valve in the first picture, replace it before the heater blows up and she doesn't have to worry about the rest of the plumbing.

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I don't know what that thing is on top of the tank. The gas was actually turned off by the gas company a few weeks ago, and she hasn't had any hot water since then.

Today, I cut out the old nasty tee and el, disconnected the gas and the vent, and then let the old tank topple to the ground. The entire bottom just fell out of it, and I just rolled it into a corner.

The new tank is firmly in place on a bed of bricks. The gas line, the dielectric nipples, and flex copper are all connected up and all the CPVC connections have been cut and dry-fitted.

VERY IMPORTANT QUESTION: I'm using several plastic screw-in type adapter fittings to go from the 1/2" PVC to the 3/4" CPVC and from the 3/4" flex copper to the 3/4" CPVC. Some of these fittings have a black seal in the middle of them. Some do not. Do I need to use teflon tape or liquid teflon on any or all of these plastic threaded fittings? Or do I just tighten the hell out of them and they will self-seal?

Use teflon tape and if your going from plastic MIP (male adaptor) into plastic FIP (female adaptor) you need it tight but to tight could crack the FIP fitting so just be aware. Have you checked the water pressure or is this a well.

Use teflon tape and if your going from plastic MIP (male adaptor) into plastic FIP (female adaptor) you need it tight but to tight could crack the FIP fitting so just be aware. Have you checked the water pressure or is this a well.

Show us a few pics when your done.

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Thanks,

It's city water, but don't know the pressure.

One other question: Are you supposed to rough up the PVC and CPVC joints with sandpaper before dry-fitting. One guy at the hardware store said you can do a better dry fit that way and it's easier to pull them back out to cement them.

Please, not PVC inside! But, the answer to your question and then some is this. You do not sand PVC or CPVC, and you can not dry fit PVC or CPVC because there is a taper in the fittings which would require you to literally hammer the fitting on, then you'd play hell getting it off. The solvent will liquify the surface of both the pipe and fitting to allow the pipe to fully seat into the fitting. This means that if there is no leeway on the end of the run, you have to measure carefully. There was a thread about this very recently, but the gist of it is measure carefully, prime inside the fitting, prime the pipe, apply solvent to the wet primer, push the fitting on to the pipe with a quarter twist (if possible) and hold the joint together without moving it for 30 seconds or so to avoid pushout. Remember, this is a solvent weld rather than an actual glued joint.

I'm all done cementing all the slip-on joints and teflon-taping all the screw-in joints. I'm really afraid that one of the cemented joints will leak. The original "plumbers" decided to run their original PVC (yes Gary, it's PVC indoors) under one floor joist and then up a few inches, and then down again under another floor joist. This flexibility might be achieved with a long piece of pipe, but when I cut out the bad section, there was a lot of pressure on the joint I was cementing. There was no play at all in the line, so notching the joist wasn't an option.

I made almost nothing from this, and I don't want to cut out anything and start over. If that joint leaks, can I use this Pasco product or anything else. I just want a temporary fix, so she can call a plumber if and when she ever gets the money.

Attached Files:

It states it is good up to 100 PSI so it will depend on the water pressure. It is a temp fix anyway and I guess you were just trying to help someone out so use it if you want just let her know about it. Be sure it says it is O.K. to use on PVC

Attached Files:

The T&P not being plumbed down won't matter as long as no one is standing next to it if it trips.

You don't need double wall where you replaced the piece of vent. Does it have any sheet metal screws holding it to the hat or the old vent. It really should to prevent any possibility of monoxide poisoning from falling off.

I hope you set the temperature low enough to keep that white pipe on the hot water side from failing. PVC pressure rating is 40% at 120 F, 30% at 130 F, 20% at 140 F, and not acceptable at all above 140 F.

The max operating pressure of 3/4" schedule 40 is 289 psi at 73 F. I would not want to see it above 130 F (leaves you about 90 psi operating pressure) and I would prefer to see it at 120 F.

Burst pressures are about 5 time those pressures, but that is the margin that takes care of the bending load on sagging unsupported pipes.

I hope you set the temperature low enough to keep that white pipe on the hot water side from failing. PVC pressure rating is 40% at 120 F, 30% at 130 F, 20% at 140 F, and not acceptable at all above 140 F.

The max operating pressure of 3/4" schedule 40 is 289 psi at 73 F. I would not want to see it above 130 F (leaves you about 90 psi operating pressure) and I would prefer to see it at 120 F.

Burst pressures are about 5 time those pressures, but that is the margin that takes care of the bending load on sagging unsupported pipes.

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Everything I used was CPVC. I believe it's rated to 180 degrees. Next time, I'll go copper all the way. I got a headache from all those solvent fumes. I set the thermostat right in the middle, but I didn't have a thermometer to check the actual temp.

One more question:

When I went to light it, I noticed dielectric nipples taped to the underside of the tank. I had used some that I bought from the hardware store. The ones that it came with had a flow restriction on one side along with a rubber flap that completely closed off one side. Does anyone know why they have that "feature" and which side goes up or down when you install them?